Emergency vehicle appliances (light bars, sirens, radios, computers, etc.) draw a considerable amount of electric power. If the appliances are inadvertently left running while the engine is off, it is possible to discharge the battery to the point that battery cannot start the engine. This happens not infrequently, and requires a service call to start the engine which will then recharge the battery.
In a vehicle that has computer equipment installed, a second problem occurs. Computers can lose information if power is abruptly cut off and computers take time to boot-up. Thus, it would be desirable to leave the computers up as long as possible.
In conjunction with the second problem, if a computer is powered up when the vehicle is shut down, the computer must then keep running when the vehicle is restarted. During engine crank, the system voltage drops well below the voltage required to keep most computers (and other electronic equipment) from crashing unless special (and therefore expensive) power supplies are used in the equipment.
Therefore, what is need is a new and improved power management system and method to address these problems. The new and improved power management system and method should protect the engine battery from being discharged by the appliances. Further, the new and improved system and method should prevent any onboard computers from crashing when the engine is being cranked, without the use of special power supplies.